Shasta Dam, 602 ft (183 m) high and 3,460 ft (1,055 m) long, on the Sacramento River, N Calif.; built 1938–45. One of the largest concrete dams in the world, it is a major unit in the Central Valley project. The dam restores navigable depths to the Sacramento River, provides flood control, electric power, and irrigation and reclamation development. Its reservoir, Shasta Lake, 46 sq mi (119 sq km), is formed by the impounded waters of the Sacramento, Pit, and McCloud rivers. The lake is included in Whiskeytown-Shasta-Trinity National Recreational Area (see National Parks and Monuments, table).